The former England midfielder has been ruled out of Wednesday's Carling Cup fourth-round tie at Wolves after a kick in the calf.
The match would otherwise have provided the 30-year-old with an excellent opportunity to get some competitive football under his belt as he looks to establish himself at City.
Hargreaves, who made a goalscoring debut for City in their third-round win over Birmingham, was released by Manchester United in the summer after three injury-ravaged seasons.
First-team coach David Platt said: "There is no worry about it. He has got a little niggle that because it is Owen Hargreaves we are talking about it.
"It is nothing much, it is just a kick in the calf. We have had it scanned and there is no pull or anything.
"He has not broken down. If he had broken down we would be talking about him being out for three or four weeks but that is not the case."
Hargreaves played 57 minutes against Birmingham five weeks ago but his only appearance since was as a late substitute in the 4-1 Barclays Premier League win over Aston Villa on October 15.
He was thought to be in contention for a place on the bench for Sunday's derby win over his former club but was not named in the squad.
Hargreaves was hampered by problems in both knees during his time at United before he suffered a hamstring injury early in what proved to be his final appearance for that club last November.
Yet while City do not want to risk him at Molineux on Wednesday, they insist that is not because they need to treat him more carefully than any other player.
Platt said: "He is there or thereabouts but the fact of the matter is he hasn't trained for three or four days.
"To go in and do one light training session and then go into it, you wouldn't do with any player. That has nothing to do with whether it is Owen or not.
"Since we came back from the international break, Owen Hargreaves has been one of the 24-25 players available for selection.
"He could well have been in the squad for the derby. He could have been in the stand, on the bench or he could have played.
"We don't look at him any more as a separate case, whereas leading up to the international break we were still in his 'pre-season' preparation.
"We are over that. He comes into the equation like any other player comes into it now.
"He came in on September 1 and we're now at the end of October.
"That's seven weeks and he's been off the training pitch five days.
"Rather than talking about what has happened in the last three years, he is now a Manchester City player and we should look at it from when he has been at Manchester City."